1. Field of the Invention
The present invention relates to a stereoscopic image display device, and more particularly, to a stereoscopic image display device for sensing device motion using a gyro sensor included therein and controlling a viewing position, and a method for driving the same.
2. Discussion of the Related Art
Services for rapidly providing information over a high speed communication network have been developed from listening and speaking services, such as provided by a telephone, to viewing and listening multimedia type services using a digital terminal for rapidly processing text, voice and image data and, ultimately, to a three-dimensional stereoscopic information communication service for providing realistic stereoscopic viewing and entertainment.
In general, the eyes form a three dimensional image based upon the principle of stereoscopic vision. Since two eyes have a disparity therebetween, that is, since two eyes are separated from each other by about 65 mm, the left eye and the right eye view slightly different images. A difference between images caused by such difference between the positions of the two eyes is referred to as binocular disparity. A three-dimensional image display device enables the left eye to view only an image for the left eye and the right eye to view only an image for the right eye based upon such binocular disparity.
That is, the left and right eyes view two different two-dimensional images. Once these images are received by the retina and sent to the brain they are processed into a three dimensional image by the brain, providing a sense of depth to the viewer. This capability is generally referred to as streography and a device having this capability is referred to as a stereoscopic image display device.
The stereoscopic image display device may be divided into many types according to three-dimensional (3D) components. For example, a stereoscopic image display device driven by an optical path difference of a lens using a liquid crystal layer is referred to as an electrically driven liquid crystal lens type stereoscopic image display device.
In general, a liquid crystal display device includes two facing electrodes with a liquid crystal layer interposed therebetween. Liquid crystal molecules of the liquid crystal layer are arranged according to an electric field generated by applying voltages to the two electrodes. The liquid crystal molecules exhibit polarization and optical anisotropy. Polarization indicates that, when liquid crystal molecules are placed in an electric field, charges in the liquid crystal molecules are concentrated to both sides of the liquid crystal molecules such that the alignment direction of the molecules is changed according to the electric field. Optical anisotropy indicates that the path or polarization of emitted light is changed according to an incident direction or a polarized state of incident light due to the elongated structure and alignment direction of the liquid crystal molecules.
Transmittance of the liquid crystal layer is changed according to the potential difference between the two electrodes. By changing transmittance on a per pixel basis, an image can be displayed.
Recently, an electrically driven liquid crystal lens which enables a liquid crystal layer to function as a lens using the above-described characteristics of liquid crystal molecules has been proposed.
That is, the lens controls the path of incident light using a difference in refractive index between a material configuring the lens and air according to positions. If different voltages are applied to the electrodes according to positions so as to generate an electric field such that the liquid crystal layer is driven, the phase of light incident upon the liquid crystal layer varies according to positions. As a result, the liquid crystal layer can control the path of the incident light similar to an actual lens. Accordingly, it is possible to obtain an electrically driven liquid crystal lens in which an optical path difference is generated in the liquid crystal layer according to applied voltage.
However, in the electrically driven liquid crystal lens, the position of the lens is fixed. If a distance between the electrically driven liquid crystal lens and a viewer is changed by rotation of the device such that the electrically driven liquid crystal lens deviates from a regular viewing position, the viewer cannot view a stereoscopic image.